Wood carving machine



Dec. 26, 1939. G. A. ANDERSON WOOD CARVING MACHINE Filed June 50, 1938 2 Sheets-Sheet 1 INVENTOR. Gkorgeddrzdaraazz A'ILIZRNEYS.

DH; 9- G. A. ANDERSON 2,185,011

WOOD CARVING MACHINE Filed June 30. 1938 2 Sheets-Sheet 2 INVENTOR. BY Gear e (Z- 427246719072,

'%I qr I ATTORNEY 5 Patented Dec. 2a, 1939 UNITED STATES PATENT OFFICE 18 Claims.

This invention relates to improvements in wood carving machines and is hereillustrated as embodied in a wood carving machine having a single cutting tool which is particularly adapted for pattern making or for individual or home use for the purpose of carving individual facsimiles of any particular work pattern which the user may desire to copy.

It is an object of this invention to provide a wood carving machine which can be easily operated and controlled and which is productive of work of high quality, the various carved portions of which are produced as to form and proportion with great exactness as compared to the original.

A further object of this invention is to provide a carving machine of the type referred to comprising a pantograph mechanism which presents the carving tool in any selected position above the work holding table and in connection with which the work may be mounted in a horizontal position on the work table or in any other position by rotatable work holding and centering means.

It is a further object of this invention to provide a wood carving machine of the pantograph type which has a novel supporting mechanism which permits bodily movement of the pantograph frame but assures the movement thereof in absolute parallelism.

More specifically, it is an object of this invention to provide a pantograph mechanism with supporting rollers which are connected to rotate together and in connection with which rack and gear means are provided for assuring uniform and simultaneous rotary displacement of both of said supporting rollers.

It is a further object of this invention to provide a novel track and rack construction for cooperation with the supporting rollers and gears. which automatically frees itself from chips or other foreign particles which would otherwise impair the uniform motion of the pantograph carriage.

A further object of this invention is to provide a pantograph mechanism having an attachment which enables the production of carved pieces of the opposite hand from the original being copied and to accomplish this result by a simple and inexpensive mechanism which. can conveniently be converted back to the usual type of pantograph machine.

Other objects are contemplated for this invention which are not specifically enumerated, as will readily appear to one skilled in the art as the following description proceeds. It is to be understood that the particular disclosure of this application is given merely by way of illustration and is not to be considered as limiting the invention in any respect as the invention is to be given the broadest possible interpretation coming within the scope of the appended claims and permitted by the prior art.

The forms of the invention here illustrated will be more readily understood by referring to the accompanying drawings, in which Figure 1 is a perspective view of one form of the invention showing the use of an attachment enabling the production of carved objects of the opposite hand;

Figure 2 is a plan view of a slightly modified construction of a wood carving machine constructed in accordance with this invention;

Figure 3 is a side elevational view of the wood carving machine shown in Figure 2;

Figure 4 is a cross-sectional view taken on the line l-l of Figure 3 and looking in the direction of the arrows;

Figure 5 is an enlarged fragmentary crosssectional view taken on the line 5-5 of Figure 8 and looking in the direction of the arrows;

Figure 6 is an enlarged elevational fragmentary view, partly in cross-section, showing the construction illustrated in Figure 5 as seen from the right of said figure;

Figure '7 is an enlarged cross-sectional fragmentary view similar to Figure 4, showing a somewhat modified form of the applicant's invention;

Figure 8 is an elevational view illustrating a modified form of holder for the pattern and the piece being carved; and

Figure 9 is a view of the work holders shown in Figure 8 as seen from the left hand side of the figure.

Referring to Figure 1, it will be noted that this form of the invention comprises a pair of frame members i lI-i 0, which are here shown as channel pieces but which can be of any suitable construction. Adjacent one end of the frame is a work table I l, which is suitably secured thereto so as to enable it to be removed when desired in order to permit the installation of other work holding means hereinafter more particularly referred to. On the top sides of the channel frames Ill-40, adjacent the opposite ends thereof, are preferably mounted and securely fixed track and rack bars i2-l2. As clearly shown, each of these bars comprises a track portion l3 which has a smooth upper surface and a tooth portion ll, constituting the gear rack. These two parts are preferably spaced by a small groove i5, which may act as a guide for the flange 15 between the rollers lateral displacement. Whereas these bars are shown as one piece in this form of the invention,

it is apparent that they may be composed of two or more pieces suitably secured together to constitute the composite whole.

Disposed on the tracks l3-l3 are rollers lB-IB which have hard and smooth surfaces adapted to traverse the same type of surfaces of the tracks, whereby the entire mechanism which is supported by the rollers is caused to have avery accurate smooth horizontal path of travel.

Integral with or fixed with respect to the rollers l6--|6 are gears l'I-l'l which are identical in character and which are disposed respectively to mesh with the teeth of the racks l4l4. The supporting rollers and their associated gears are so constructed with relation to the track and rack bars that the entire support falls on the rollers, which in turn hold the gears in mesh with the racks, but so that none of the supporting weight is carried on the gears and racks themselves. Each of the gears, and its attached roller, is connected to the central rotating tube l8, which provides a rotating assembly extending from one track to the other which is suitably mounted on an axle l9, preferably by suitable anti-friction bea ings.

The axle l9 extends entirely through the tube I 8 and projects beyond the rollers Iii-l6 to provide ends which have the radially disposed spindles 20-20 extending therefrom in diametrically opposed directions.

These pindles have socketed ends which form pivotal mountings for the point bearing members 2l-2I adjustably mounted in the opposed portions of the yoke 22. The upper point bearing 2| may be permanently mounted, while the lower point bearing is adjustable by means of screw heads 23, so that suitable adjustment of the pivot mounting may be obtained.

It will be notedthat the diametrically extending sp ndles 202ll' on the oppo ite sides of the machine extend from the same points in the circumference of the axle, so that they provide pivot supports for the yokes 22-22 on parallel axes The yoke members 2222 preferably terminate at their upper ends in frame connecting collars 25-25, as clearly shown in Figure 1. One of the collars 25 has permanently secured therein a frame bar 26 which extends to the rear of the machine and provides a mounting for a counterbalancing weight 21 which may be adjusted therealong and held in any adjusted position by means of the set screw 28.

This frame bar terminates at its forward end motor may be of any suitable construction and per se constitutes no part of the present invention, provided only that it is of suitable construction to do the work intended therefor.

Extending from the lower end of the motor is a holder 38 for a suitable cutting tool 39, which is thus presented in a suitable position for engaging the work held on the table H, The f am bar as also has a lug 40' provided with a bearing opening 4|, which is disposed opposite to the lugv 33 of the frame bar or arm 26. These lugs are 7 adapted to be connected by an arm (not shown) for the formation of a usual pantograph mechanism when the piece being carved is to be of the same hand as the work being copied. This connecting link will cause the cutting tool to move to the right when the tracing pin moves to the right, and vice versa.

However, as shown in the drawings, this device further has a bracket secured to the frame bar 26 at a location between the collar 25 and the adjustable counterweight, andthe frame bar 35 has the bracket 46 mounted thereon be- .tween the frame collar 25 and the electric motor 36. In other words, as clearly shown in the drawings, these brackets 45 and 46 are disposed on opposite sides respectively of the plane of the axes of the yokes 2222 on the spindles 2020. Each of the brackets 45 and 46 has a yoke at its inner projecting end for receiving respectively the ends of a connecting link 50, which is piv-' oted to each of said yokes by means of a pivot pin which extends through openings in'each yoke and openings in the ends of the link, and which may be removed by means of the wing bolts 5I--5l.

The link 50 thus serves as a means for imparting to the cutting tool 39 a movement corresponding to the movement of the tracer pin 30, but in the oppositedirectiom, Thus, with the link 50 installed as above described, movement of the tracerpin- 30 a predetermined amount to the right will impart a corresponding movement to the cutting tool 39, but to the left instead of to the right. This, of course, will result in the production of an accurate copy of the original, except, however, that the finished work will be of the opposite hand.

It is apparent that if work of the same hand as the original is de ired the link 50 may be quickly removed from the machine by turning the wingbolts 5i and another link corresponding to the link 50, but somewhat greater in length, inserted between the lugs 33 and 49', respectively, and pivotally installed by means of the same or similar wing bolts. The several named links above referred to, but not shown, should be of such a length that when connected to lugs 33 and 40 a parallelogram is formed wherein one of the sides represented as the distance between tracer pin 30 and cutting tool 39 is the same as the side represented as the distance between spindles 2020.

In operation it is apparent that, irrespective of the installation of the link 50, a pantograph mechanismv is provided which has a tracing arm and a cutting tool which are connected for parallel or related movement in the manner intended, and that as a whole these arms are pivotally mounted for swinging on parallel axes provided by the yokes 2222, and that further the entire assembly is adapted to be moved bodily along the tracks l3-l3 in absolute parallelism, whereby the accuracy of the carving operation is assur d. It is further apparent that the axle I9 which pivotally supports the yokes 2222 forms a horizontal axis on which the entire assemblymay be lifted up and down as when the tracing pin and cutting tool are lifted and lowered during the use of the machine. It will further be apparent that'the counterweight 21 may be adjusted to balance the forwardly extending portions of the machine in the desired manner to give facility and accuracy of movement in operation.

An essential feature of this invention resides in the gear and rack mechanism; which by virtue of the connecting tube I8 assures a uniform rolling movement on both tracks, where all liability of the mechanism becoming out of parallel is eliminated.

Referring now to Figures 2 to 6, inclusive, a somewhat modified form of the invention is illusti'ated in which the frame is composed of a pair of spaced parallel channel members I 00-I00 having a suitable support and suitably crossbraced and upon which is mounted adjacent one end thereof a work table IN. This table may be held in position by suitable screws I02, as clearly shown in Figure 2. The work table may be further provided with slots I03 for accommodating suitable clamping means for holding the work on the table.

Adjacent the opposite ends of the frame channels I00I00 are track and rack bars I04-,I04. These are held by suitable screws or other holding means I05 which extend upwardly through the top flange of the channels I00--I00.

As clearly shown in Figure 3, each of the rack bars I04 has an upper surface I06 which is smooth and hard and forms a supporting surface for rollers hereinafter more fully described. On the inside of each of the track bars is a plurality of laterally extending teeth which have their upper surfaces cut collectively to provide the gear rack III. Each space between the teeth is of substantial depth, whereby ample space is provided for any wood chips or dust or other foreign matter that might tend to accumulate on the rack. In this way the absolute horizontal movement is assured.

As shown in Figure 4, rollers I0II0I are provided for supporting the pantograph mechanism on the tracks I04I04. Each roller has a lateral edge which is in engagement respectively with the shoulders I08-|08 of the track, whereby the rollers are held against lateral displacement. Each roller preferably has a sleeve member I09 on which are mounted the gears IIO-I I0 which are suitably disposed for meshing engagement with the gear racks IIIIII. The sleeves I09I09 are connected at each end respectively to a tube II2 by means of holding screws II3--I I3. This tube connects the rollers and gears on opposite sides of the machine and forms a unitary rolling assembly. Extending through this assembly is an axle I I4 which has bearing surfaces at its outer ends in engagement with the antifriction bearings II5II5 carried in the race rings provided in the roller constructions, as shown in Figure 4. The axle II4 has parallel transverse openings II6I I6 therethrough in which are mounted the bearing spindles II'I-I I'l respectively held by means of the set screws II8-I I8. These bearing spindles preferably are constructed as shown in Figure 4, with pointed upper ends II8 --I I8 and socketed lower ends II9-II9. The lower ends are of smaller diameter than the upper ends, whereby the pins may be dropped into position from above and held by the set screws I I8--I I8.

The socketed lower ends form female bearing members in engagement with the pointed ends I20-I20 of the adjustable bearing screws I2l--I2I, which are screw-threaded in the openings I22-I22 of the yoke members I23-I23. These bearing pins may be locked in position by means of lock nuts I24--I24. The yoke members are provided with female bearing recesses I25-I25 at their upper portions for pivotal support on the upper bearing points II8 --I I8.

As thus shown in Figures 2 and 4, the yoke I23 on one side of the mechanism has integrally formed therewith a frame bar I26 which extends in opposite directions from the yoke and is provided at one end with a holding collar I21 for mounting the tracer pin I28, held by means of the lock screw I29. The opposite end of the frame bar I26 terminates in a reduced portion I30, serving as a sliding support for the counterweight I3I, which may be slid therealong and held in any adjusted position by the lock screw I32. This bar is also provided with a threaded recess I33 adjacent the tracing pin, in which may be mounted the bearing pin I34 for pivotally attaching the connecting link I35.

The yoke on the opposite side of the machine has integrally formed therewith a frame bar I36 which extends forwardly and is formed to provide a bracket face I31 for mounting the electric motor I38. This motor is so positioned that the axis of its rotor is vertically disposed, whereby it will serve as a means for mounting a cutting tool disposed on an axis parallel to the axis of the tracing pin I20. The motor is equipped with suitable electrical connections (not shown) whereby it is operated by turning a suitable switch. The bar I36 is also equipped with a threaded opening I39 for mounting a bearing pin I40 for pivotally connecting the opposite end of the connecting link I35.

As best shown in Figure 4, the yokes l23--I23 are preferably made in the form of housing plates which substantially enclose and protect the vertical spindles, the ends of the axle and to some extent the supporting rollers and associated gears. These housings may be equipped with suitable strengthening ribs I4I-I4I, shown in Figures 2 and 4.

Carried on the ends of the axles between the rollers I0'|-I0I and the bearing spindles II! are located members I42-I42, which have a central opening to fit over the reduced ends of the axle and have upstanding ends provided with a lug I43 for engaging the upper part of the spindle II1 so as to hold the frame when in a lifted position as hereinafter more fully described. These members have inwardly turned ends I44 at their bottoms which underlie the upper horizontal flange of the channel frame members I00--I00, whereby the entire rotating assembly and supported carriage are held against upward movement. The entire pantograph mechanism is thus held against accidental lifting off of the track or otherwise becoming accidentally displaced.

Secured to the wall of members I42I42, by means of glue or any other desired material, are wipers I4'lI41 in wiping engagement with the upper surfaces of the track. One of these wipers is positioned at each side of the roller, whereby the track is thoroughly cleaned in either direction of movement to assure the provision of a clean smooth surface on which the rollers may travel. This, coupled with the novel rack construction, assures at all times that the carriage will not meet any obstructions which would prevent its proper operation.

Furthermore the members I42--I42 are additionally provided with an inwardly turned edge I48-I48 and extending between the edges on opposite sides of the machine is a U-shaped housing I48 secured thereto and serving as a guard which, together with the inturned edges a least, around the sides of the mechanism.

The horizontal travel of the carriage on the tracks is limited at the extreme ends by contact between the members |45-|45 and lugs l49-l49 located at the ends of the tracks, as shown in Figure 3.

A slightly modified form of assembly is shown in Figure 7 which differs from the form illustrated in Figure 4 in that the yokes are carried on a tube member 2|2, which is in turn mounted in surrounding relationship to a rotating axle H4. The ends of the axle havevfixedly secured thereto gears H0 and a roller 20'! which are mounted respectively on a rack 21! and a track 204. These racks and track bars may be constructed substantially like the corresponding parts shown in Figure 4, with the exception that as here illustrated the track is on the inside and the rack is on the outside. These rack and track bars are mounted on frame channel members 200 in substantially the manner previously described in connection with the other modification.

Mounted on the tube 2I2 is a bracket member 2 l5 which is equippedwith bearing pins 2|! and 2l9, respectively, which pivotally mount the yoke members 223223 in substantially the manner previously described. Anti-friction bearings 2l6-2l6 may be provided between the axle 2M and the brackets 2l5.

As illustrated in Figures 8 and 9, modified work holders may be provided constructed substantially as shown and comprising brackets 300 adapted to overlie the upper flange of the channel frame I00 and be held in any adjusted position therealong by means of the lock screws 30L This bracket is equipped with an upstanding portion 302 which has a pivot 304 therein for rotatably mounting the work holding plate 305. The work holding plate is preferably equipped with a plurality of holes 306 equally spaced around the periphery thereof, which may be successively presented in alignment with the end of a pin 30'! held in an opening 308 in the upstanding portion 302. The work holding plate is further equipped with pointed projections 3|0 on the face thereof for engaging and immovably holding a piece of wood or other material to be worked on in the desired position.

, The cooperating member comprises a similar bracket 300 having a holding screw 30! and an upstanding portion 3|5, adjacent the upper end of which is a work holding and centering device 320. This device is pivoted to a screw 32l which may be screwed into and out of a threaded opening in the bracket or upstanding portion 3l5 and held in any adjusted position by means of the lock nut 322. This holding and centering device has a circular conformation provided with an edge 323 and a centering pin 324. The centering pin is disposed on the same axis as one of the projections 3I0, which serves as a centering pin on the work holding plate 305, so that the piece of wood being worked upon may be placed between the centering pins and the holding plate by moving the brackets 300 into a position closely to embrace the work piece.

As shown in Figure 9, an identical pair of holding devices is provided on the opposite channel frame part I00, whereby the pattern is properly presented in convenient relationship to the end of the tracer pin.

In operation the pattern and the piece of wood to be carved are placed in their respective holders and the initial carving is accomplished by tracing the pin over the surface of the pattern. After the first portion of the carving operation has been completed the pattern holder is rotated around to the next position of adjustment by I placing the holding pin 30'! into the next hole 303. A corresponding adjustment is made on the work holder and the carving operation continued.

Thereafter the pattern and the work piece are 403 for clamping a second tracing pin 404 which is disposed in horizontal position for engagement with the inner surface of the guide plate 400.

With this attachment, the vertical and horizontal tracing pins may be suitably adjusted for engagement with the work table and guide plate, respectively. When so adjusted, the tracing pins may be caused to travel from front to back of the table and plate, whereby to give to the cutting tool 39 a predetermined movement on a fixed horizontal line. Thereafter the pins may be readjusted to cause a movement in a slightly different horizontal line, such ,as would result froma slight vertical as well as horizontal-displacement. With the new adjustment a second horizontal cut may be made, and so on throughout the course of a plurality of cuts, each with its particular adjustment of the tracing pins. When the adjustments are made according to a predetermined plan, the series of horizontal cuts may form a molding or similar piece of any desired shape.

What is claimed is:

1. A carving machine of the character described, comprising a support, a pair of spaced tracks on said support, a pair of rollers mounted on said tracks connected for rotation together, a pantograph mechanism having a tracing means and a carving tool carried by said rollers, gear racks disposed in association with said tracks, and gears fixed to rotate with said rollers in mesh with said racks, respectively.

2. A carving machine of the character described, comprising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said ;member, a link for pivotally connecting said arms, a tracing pin carried by one of said arms, and a carving tool carried by the other of said arms.

3. A carving machine of the character described, comprising a support, a pair of spaced When this type of plate is used, a

tracks and associated gear racks mounted on said support, connected rollers supported on said traclm each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried by one of said arms, and a carving tool carried by the other of said arms, one of said arms having an extension on the opposite side of its pivot and having a counterweight adjustably mounted on said extension.

4. A carving machine of the character described, comprising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried by one of said arms, and a carving tool carried by the other of said arms, said arms having connections for selectively receiving said link to connect said arms for movement in the same direction or for movement in opposite directions.

5. A carving machine of the character described, comprising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried adjacent the end of one of said arms, an electric motor carried on the end of the other of said arms, and means carried by said motor for mounting a carving tool for rotation by said motor.

6. A carving machine of the character described, comprising a support, a pair of spaced tracks on said support, a pair of rollers mounted on said tracks connected for rotation together, a pantographmechanism having a tracing means and a carving tool carried by said rollers, gear racks disposed in association with said tracks, and gears fixed to rotate with said rollers in mesh with said racks, respectively, said ear racks having deep spaces between adjacent teeth whereby dirt accumulations will not affect the movement of the associated gears therealong.

7. A carving machine of the character described, comp-rising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried by one of said arms, a carving tool carried by the other of said arms, and wipers carried by said member disposed in engagement with said tracks adjacent said rollers.

8. A carving machine of the character described, comprising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said and a carving tool carried by the other of said arms, said racks comprising a plurality of teeth formed from laterally extending lugs having deep spaces therebetween.

9. A carving machine of the character described, comprising asupport, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on. said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a. pair or arms pivotally mounted on said member, a. link 1or pivotally connecting said arms, a tracing pin carried by one of said arms, and a carving tool carried by the other of said arms, said member and arms being horizontally tiltable on the axis or said rollers.

10. A carving machine of the character described, comprising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried by one or said arms,

.a carving tool carried by. the other of said arms,

said member and arms being horizontally tiitable on the axis or said rollers, and means carried by said member for limiting the upward tilting movement thereof.

11. A carving machine of the character described, comprising a support, a pair or spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried by one of said arms, a carving tool carried by the other of said arms, and means carried by said member for holding said rollers against accidental displacement from said tracks.

12. A carving machine of the character described, comprising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried by one of said arms, a carving tool carried by the other of said arms, and means carried by said carriage for substantially enclosing and protecting said rollers.

13. A carving machine of the character described, comprising a support, a pair of spaced 14. A carving machine of the character described, comprising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried by one of said arms, a carving tool carried by the other of said arms, means mounted on said support for holding a pattern, and other means for holding a workpiece.

15. A carving machine of the character described, comprising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried. by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried by one of said arms, a carving tool carried by the other of said arms, means mounted on said support for holdv ing a pattern, other means for holding a workpiece, and a guard mounted on said member between said holding means and said rollers.

16. A carving machine of the character described, comprising a support, a pair of spaced tracks and associated gear racks mounted on said support, connected rollers supported on said tracks each having an associated gear connected thereto, said gears being disposed in mesh with said racks, respectively, a member carried by said rollers, a pair of arms pivotally mounted on said member, a link for pivotally connecting said arms, a tracing pin carried by one of said arms, a carving tool carried by the other of said arms, an adjustable counterweight for said arms, and means for limiting the movement of said arms under the influence of said counterweight.

GEORGE A. ANDERSON. 

